biogeochemistry

Pacific Northwest National Lab has an exciting opportunity for a post-masters intern to work with an interdisciplinary team, with a focus on biogeochemistry, microbiology, and hydrology. Part of this position will contribute to the global WHONDRS consortium (whondrs.pnnl.gov).

Location

Field research infrastructural for studies on forest, soils, streams, lakes and mires in the boreal landscape

Detailed Site Description:

Krycklan Catchment Study (KCS) is the most instrumented and well-studied meso-scale catchment in the boreal region. The 70 km2 KCS builds on three decades of catchment science that grew up around the Svartberget field station and is currently one of the most ambitious projects integrating water quality, hydrology, and aquatic ecology in running waters in the north. At present, KCS includes 18 intensively instrumented and continuously monitored sub-catchments, an extensive soil sampling program, comprehensive lake carbon-balance studies, several long-term field experiments, and a large set of ancillary data. To date, close to 20,000 stream and soil water samples have been collected (with duplicate sample archived in freezer) and analyzed providing approximately 10 million unique water chemistry observations. At the center of the catchment the 150 m ICOS (pan-European Integrated Carbon Observatory System) research tower is placed for measuring exchange of energy, water and carbon that will allow for one of the best assessments of full carbon balance at a landscape scale that presently exists anywhere in the world. At presently over 100 research projects are being conducted involvning several hundered researchers from all over the world.

Location

Critical zone processes in waste water irrigated fields for over a century.

Detailed Site Description:

The Mezquital valley, 80 km north of the metropolitan area of Mexico City (MAMC), is an example of a low cost Soil-Aquifer-Treatment system, in which untreated sewage and surface runoff collected within the closed basin of Mexico, are used to irrigate mainly fodder crops and maize. The valley is at 2100 m asl, and has a temperate semi-arid climate. Natural vegetation corresponds to xerophytic shrublands, but irrigation has changed the natural hydrologic environment and the land cover. Today more than 90,000 ha are cultivated mainly with lucerne and maize cropped in rotation. The soil moisture regime has changed from ustic to udic, and there is an artificial groundwater recharge of 6 m3/s of the semi-confined upper aquifer. Supply water for more than 500,000 inhabitants of the valley is provided by this semi-confined aquifer.

Our working group manages a critical zone observatory in this area since 1990. The objective is to evaluate the impact of long-term irrigation on the soil, crop, groundwater and air quality in the region. We also collaborate in assessing the impact on human health. We do this following two main strategies:

We have repeatedly sampled fields irrigated for different lengths of time with untreated wastewater in 1990 and 2009, respectively. Fields are distributed among the dominant soil types, namely Leptosols, Phaeozems and Vertisols (Calciustolls and Pellusterts). In these fields we have sampled soils (by genetic horizon and also composite samples from the upper 30 cm) and crops, and have analyzed them for nutrients and pollutants as heavy metals, pharmaceuticals, detergents and salts. We have also studied the microbial communities and their activity.
Since 2008 we are monitoring critical zone processes during single irrigation events to follow groundwater recharge, nutrient and pollutant leaching as well as greenhouse gas emissions. This has been done along a transect crossing the extended piedmont of the valley. We have installed deep piezometers (30 and 25 m deep), observation wells (at 1, 2, 4 and 5 m depth) and suction cup lysimeters in the first 4 dm of the soil. We also installed gypsum blocks, TDR probes, tensiometers to follow moisture contents and water tension; Pt-electrodes to monitor redox potentials and static chambers to measure gas emissions.

We also have sampled fields and monitored processes in rain-fed agricultural fields as well as in plots covered by the natural vegetation for comparison.

Field Site Type:

International CZO

Registration:

Registered

Network(s):

LTSE

Study Start Date:

1990

Mean Annual Precipitation:

640 millimeters / year

Average Annual Temperature:

17°C

Average Summer Temperature:

18°C

Average Winter Temperature:

16°C

Land Cover:

Agriculture- Crops

Geology:

other igneous

Soil Order:

Mollisol

Vertisol

Hydrology: Name:

Upper Panuco

Hydrology: Surface water stream order:

Second Order

Hydrology: Surface water - Stream Flow Performance:

Perennial

Hydrology: Groundwater:

Arrangment of Aquifer Components - Three unit system of an unconfined aquifer, confined aquifer and a confining bed

Location

A coastal margin observatory dedicated to the study of organic matter and carbon cycling, ecosystem pattern and process, across a land-sea gradient.

Detailed Site Description:

Terrestrial materials exported from coastal watersheds influence marine food-webs and carbon budgets across the globe, yet much is unknown about the fundamental processes of land-sea carbon cycling or system response to climate change. On an outer-coast island near the center of the Pacific Coastal Temperate Rainforest (PCTR) in North America, the Hakai Institute has developed a long-term coastal margin observatory to examine the flux of terrestrial materials from land to sea – the origins, pathways, processes and food web consequences – in the context of long-term environmental change.

Our study area is Kwakshua Channel and all the land that drains into the channel (approximately 7000 hectares) - a natural laboratory well suited to the study of terrestrial-marine coupling in the hypermaritime coast of western North America. The terrestrial environment is ecologically and physically diverse, varying from bogs and forested wetlands to productive riparian forests. Streams are characterized by high levels of terrestrial organic matter, with concentrations varying across time and space. Kwakshua channel itself is a well-defined and accessible marine waterbody in which to observe physical mixing, microbial processing, food web uptake and ecological interactions.

Beginning in 2013, we established an integrated and multi-disciplinary study across the land-sea gradient. We are using LiDAR and other remote sensing data to examine landscape controls on terrestrial ecosystems and watershed exports. Focusing in on the sources of dissolved organic matter on land, we established a network of terrestrial ecosystem plots across a landscape gradient. Plots are used to examine community composition, stand dynamics, and soil processes, with a subset of plots outfitted for remote monitoring of soil dynamics with sensors. At stream outlets, we use a year-round sampling program and sensor network to quantify, at high temporal resolution, the amount and character of terrestrial exports from seven focal watersheds. Nearshore oceanographic conditions and plankton communities are also monitored year round, adjacent to stream outlets and at other nearshore stations within and outside the channel. Similarly, we conduct year-round sampling of microbial communities - including bacteria and protists - across the terrestrial, freshwater and marine sites.

The Critical Zone - from bedrock to tree-top - indeed plays a critical role in controlling the export of organic materials from coastal watersheds. Consequently, we use the framework of a critical zone observatory to study the watersheds of Calvert Island.

Research Topics:
Vegetation structure and production; dynamics of detritus in terrestrial and aquatic ecosystems; atmosphere-terrestrial-aquatic ecosystem linkages; heterotroph population dynamics; effects of human activities on ecosystems.

Description:
The Hubbard Brook Experimental Forest (HBEF) is a 3,160 hectare reserve located in the White Mountain National Forest, near Woodstock, New Hampshire. The on-site research program is dedicated to the long-term study of forest and associated aquatic ecosystems.

History:
The HBEF was established by the USDA Forest Service, Northeastern Research Station in 1955 as a major center for hydrologic research in New England. In the early 1960's, Dr. F. Herbert Bormann and others proposed the use of small watersheds to study element cycling. In 1963, the Hubbard Brook Ecosystem Study (HBES) was initiated by Bormann and Drs. Gene E. Likens and Noye M. Johnson, then on the faculty of Dartmouth College, and Dr. Robert S. Pierce of the USDA Forest Service. They proposed to use the small watershed approach at Hubbard Brook to study linkages between hydrologic and nutrient flux and cycling in response to natural and human disturbances, such as air pollution, forest cutting, land-use changes, increases in insect populations and climatic factors.